Purple Subject photographing Blue

[Rock Lobster]

Has anyone else noticed this phenomenon ? I recently took some pictures at a friends graduation with my S3IS, their graduation robes were a deep purple color. but in all all my pictures they came out bright blue!
At first I thought something was up with my camera, but then I could see the screens of several other peoples digital cameras as they were taking pictures and on their screens the graduation robes were also bright blue.
The two pictures show the original picture and then how they should have looked after I edited it in Photoshop

[Paradox]

It could be something along the lines of how much red and blue light the robes reflect...they could reflect much more blue light than red so the sensor picked up on that. It could be to do with blue light's much higher frequency than red light having some effect on the sensor receiving different levels. However I think it's much more likely that your camera was trying to correct for something and buggered it up. ;) Don't really know what though, that's a pretty huge mistake.

[Graystar]

This is just something that camera’s do.

Purple is not a spectral color. That means that it cannot be represent with a single wavelength of light (whereas just about every other color can be.) Therefore, purple doesn’t really exist except in our minds, where our brains combine equal amounts of red light and blue light to make purple.

The camera, however, takes matters a little more literally. It knows that humans perceive red as being brighter than blue, so blue gets a boost in gain and red gain is turned down in order to maintain neutrality. However, this messes up the color purple, since the balance between red and blue has been shifted towards blue.

There’s a commercial Photoshop plugin that’s supposed to help with this issue. I use the color channels tool to fix the problem.

[SpecialK]

This is just something that camera’s do.

Purple is not a spectral color. That means that it cannot be represent with a single wavelength of light (whereas just about every other color can be.) Therefore, purple doesn’t really exist expect in our minds, where our brains combine equal amounts of red light and blue light to make purple.



Huh? I see purple.
37753


I would guess some weird combination of dye reflectance, UV sunlight, and sensor is the cause. Otherwise, purple flowers would be...blue.

Roy G. Biv

[Graystar]

Huh? I see purple.
You see indigo and violet...like it says at the bottom of the chart.

"Purple is sometimes confused with the more narrowly-defined spectral color, violet."
http://en.wikipedia.org/wiki/Purple#Purple_versus_violet
http://en.wikipedia.org/wiki/Purple

Here's info on violet.
http://en.wikipedia.org/wiki/Violet_(color)

[viewfinder]

I would guess some weird combination of dye reflectance, UV sunlight, and sensor is the cause. Otherwise, purple flowers would be...blue.

Roy G. Biv

You are right about the purple flowers being blue.
I was taking macro shots of flowers this past weekend using my S3IS and the pictures I took of pansy flowers which were violet/purple in colour, appeared blue in colour in the camera image. The violet colour could only be seen(barely) around the edges of the petals.

[Graystar]

I would guess some weird combination of dye reflectance, UV sunlight, and sensor is the cause. Otherwise, purple flowers would be...blue.

That's quite literally true. They ARE blue...and red...at the same time (that is the definition of purple.) We see the color as purple but the camera sees a red and a blue. This is unlike violet, where we see violet and the camera sees violet.

The camera’s response to blue is different than the camera’s response to red due to differences in luminosity. Blue is boosted, red is suppressed, and you see purple objects as blue.